先買權的制度運作是實務上重要問題，不過，既有相關學 說研究仍有不足。例如「部分共有人以多數決出賣不動產時， 他共有人之先買權」的議題，即有許多爭議待釐清，且內政部 目前研商的土地法部分條文修正草案中，該先買權規定是修正 的重點之一。本文先釐清土地法第34 條之1 第1 項及第4 項 的規範意旨，再依序探討部分共有人以多數決出賣不動產時， 他共有人之先買權賦予的理由及標的。本文著重於不動產的有 效利用與相關當事人的利益衡量、成本效益分析，就既有的學 說、實務見解及修正草案予以回應，並提出解釋論與立法論上 的建議。 本文以為，部分共有人以多數決出賣共有不動產時，他共 有人有先買權，其先買權的標的為同意出賣之共有人的應有部 分；在部分共有人以客觀上顯不相當對價而多數決出賣不動產 的情形，如他共有人死亡，繼承人有無不明，則他共有人的遺 產管理人得主張先買權。

The system of the right of first refusal is an important issue in practice. However, the existing studies are insufficient. For example, there are controversies regarding “a right of first refusal when the majority of the coowners sell the real estate.” Among the draft amendment on partial articles of Land Act discussed in the Ministry of the Interior now, such right of first refusal is one of the key points. First of all, this study clarifies the purposes of the first and the fourth paragraphs of Article 34-1 of the Land Act. This study then explores the reason and the object of the right of first refusal in turn when the majority of the co-owners sell the real estate. This study emphasizes effective utilization of the real estate and the interests of the concerned parties and stresses on the cost-benefit analysis. This study discusses the existing doctrine, practice, and the draft amendment and makes some propositions in explanation and legislation. This study holds that there is a right of first refusal when the majority of the co-owners sell the real estate and the objects are the shares of the coowners who agree to sell. When the majority of the co-owners sell the real estate for improper value obviously and the other co-owners were died, the manager for the other co-owner’s property may claim a right of first refusal if it is not clear whether or not there is an heir.